Effect of Sn ratio on the photocatalytic degradation of methylene blue and soot of ink by TiO2–SnO2 nanostructured thin films

The photocatalytic performance of rutile-, anatase- and mixed-phases of nanocomposite TiO2–SnO2 thin films, with different Sn ratios was tested. The absorption spectra of the prepared films show enhancement of high absorbance in the visible region for samples with Ti to Sn ratios of 3:1. Degradation of both methylene blue (MB) and soot of ink (SI) was examined by transmittance change under UV–vis irradiation. Sn doping improved the photocatalytic activity of the films. The results reveal that the smoother the sample surface and smaller the particle size; the highest the photocatalytic activity. Moreover, thin films doped with Ti to Sn ratios of 50:1 and 3:1 photocatalyst could more readily photodegrade MB and SI under visible-light irradiation. The high visible-light catalytic activity of the prepared photocatalyst resulted from the high absorbance in the visible-light range and also the reduced electron–hole recombination rate.